This disclosure relates to a medical device and more particularly to an implantable therapeutic substance infusion device also known as an implantable drug pump.
The medical device industry produces a wide variety of electronic and mechanical devices for treating patient medical conditions. Depending upon medical condition, medical devices can be surgically implanted or connected externally to the patient receiving treatment. Clinicians use medical devices alone or in combination with therapeutic substance therapies and surgery to treat patient medical conditions. For some medical conditions, medical devices provide the best, and sometimes the only, therapy to restore an individual to a more healthful condition and a fuller life. One type of medical device is an implantable therapeutic substance infusion device.
An implantable therapeutic substance infusion device is implanted by a clinician into a patient at a location appropriate for the therapy. Typically, a therapeutic substance infusion catheter is connected to the device outlet and implanted to infuse the therapeutic substance such as a drug or infusate at a programmed infusion rate and predetermined location to treat a condition such as pain, spasticity, cancer, and other medical conditions. Many therapeutic substance infusion devices are configured, so the device can be replenished with therapeutic substance through a septum while the device is implanted, so the time the device can be implanted may not be limited by therapeutic substance capacity. An example of an implantable therapeutic substance infusion is shown in Medtronic, Inc. product brochure entitled “SynchroMed® Infusion System” (1995).
Electrically powered implanted therapeutic substance infusion devices can require replacement once implanted due factors such as battery consumption, corrosive damage, and mechanical wear. Since replacement of the implanted device requires an invasive procedure of explanting the existing device and implanting a new device, it is desirable to only replace the infusion device when replacement is required. Replacement of previous implantable infusion devices was typically scheduled based upon a worst-case statically forecasted elective replacement period. The worst-case scenario typically resulting in the implanted infusion device being replaced several months or even years before the implanted infusion device required replacement. Some previous implantable pulse generators such as pacemakers have monitored a single sensed battery condition to estimate replacement time for the implanted device or battery such as shown in U.S. Pat. No. 6,167,309 “Method For Monitoring End Of Life For Battery” by Lyden (Dec. 26, 2000).
For the foregoing reasons, there is a need for an implantable therapeutic substance infusion device with active longevity prediction to increase the infusion device's effective life, reduce the need for a clinician to perform static longevity forecasts for therapy changes, facilitate elective replacement scheduling for the convenience of the patient and clinician, and many other improvements.